The invention relates to a safety belt buckle for receiving and locking an insertion tongue, having a housing with an insertion slot for the insertion tongue with a spring-loaded ejector arranged in the insertion slot, and a locking device cooperating with a cutout of the insertion tongue in a locking position, whereby the locking device locks the insertion tongue in the insertion slot, and further having a spring-loaded and two-part sliding key for releasing the locking device, the sliding key comprising a sliding key body and a key button which is insertable into the sliding key body, whereby a spring in the form of a sensor spring is arranged between the sliding key body and the key button for holding the key button in an essentially extended position when acceleration forces occur, and whereby, when the key button is manually activated, a relative displacement between the key button and the sliding key body is translated into the actuation of the locking device.
A safety belt buckle of the aforementioned kind is described in DE-OS 38 11 429; it is suggested that the sliding key body is locked relative to the casing of the safety belt buckle so that, when acceleration forces occur, the safety belt body remains in its resting position whereby the insertion of the key button caused by the acceleration forces will not release the sliding key body from its locked position within the safety belt buckle casing. Only the manual actuation of the key button releases the sliding key body from its locked position within the safety belt buckle casing so that with the progressing unlocking stroke the sliding key body causes the unlocking of the locking mechanism.
The known safety belt buckle has the disadvantage that the locking device of the sliding key body within the safety belt buckle casing which is to be released causes a resistance against the opening movement of the safety belt buckle performed by the user so that thereby the operating comfort of the safety belt buckle is reduced. Furthermore, the locking forces, on the one hand, and the opening forces which result from the insertion of the key button into the sliding key body, on the other hand, must be exactly coordinated with one another in order to prevent, with a due safety margin, an unlocking of the sliding key body within the safety belt buckle casing. Also, the known safety belt buckle is of a complicated design because the means for locking the sliding key body, on the one hand, and for releasing the locking device, on the other hand, must be supported in a respective manner.
It is therefore an object of the present invention to improve a safety belt buckle of the aforementioned kind such that the safety belt buckle is impact-protected against acceleration forces acting in the actuation direction of the sliding key while maintaining a high operating comfort, whereby the design of the safety belt buckle should be simple.